It is known in the art to use a disc or diaphragm valve to control fluid flow. However, the advantages of an electromagnetically actuated diaphragm valve and applications thereof, such as for crankcase inlet control of a two cycle engine, have apparently not been previously known. Actuation of a flow-control valve by means of an electromagnet provides convenience and flexibility difficult if not impossible to match. However, the use of electromagnets may be complicated by trade-offs in movement between the on and off positions, electrical power, initiating force and overall size.
A well-known diaphragm-type spring application is in the conventional and familiar household oil can, where the perimeter is fixed and the center is deflected. The spring has about the desired load-deflection characteristic for the applications to be described and the spring itself is in contact with the fluid medium to be controlled. However, the device functions as a pump where the volume and rate of flow are determined by the diaphragm position and rate of deflection.
The present invention employs a diaphragm functioning only as a valve which seals a flow path. Diaphragm-type springs have been employed for many years where compactness in the direction of loading and the peculiar variety of load-deflection characteristics available are desired spring design features. The diaphragm spring is also known as a Bellville, disc or ring spring. For a valve application, the type of load-deflection characteristic desired is shown in FIG. 1. Although a perfectly symmetrical characteristic is shown, this need not be an important requirement.
The embodiments to be described employ one or more relatively thin sheet segments of variously shaped resilient, flexible material, as a disc, which performs the sealing function of a valve and may provide the springiness required to return the thin sheet valve to its null or closed position. Furthermore, each valve disc is preformed to introduce internal stresses that permit the valve to assume either of two equilibrium positions. Because of its relative thinness, this type of valve will be referred to as a diaphragm valve. Preferred actuation is by an electromagnet, but other force generators, such as a fluid mechanical pressure difference, are also possibilities.
These and other features and advantages of the invention will be more fully understood from the following description of certain specific embodiments of the invention taken together with the accompanying drawings.